Google has a media event planned for Tuesday morning at the Googleplex where it plans to unveil "innovations in two of our most popular products," the company said in an e-mail to InternetNews.com.

But some details are already leaking out. A number of publications and rumor sites have reported that Google (NASDAQ: GOOG) plans to unwrap an update to Gmail that brings Twitter-like features to the e-mail program. Gmail already lets users set status updates, much like Twitter, Facebook and other Web apps, and also to engage in chat sessions with other Gmail users.

Google plans to announce a new module to the Gmail screen that will feature a stream of updates from people the user chooses to connect with, according to a report in the Wall Street Journal. This kind of shared activity stream has been popularized by Facebook and Twitter, and more recently by Yahoo (NASDAQ: YHOO). The latest version of Yahoo Mail lets you see, for example, when friends have added pictures to the Flickr photo-sharing site.

The move comes at a time of hyper-competitive activity among social networking, media and search sites as they race to add features such as real-time results, and jockey to attract new users and hang on to those they already have.

Just last week, Facebook unveiled a new design that includes a left-hand column showing which of your friends are online and applications similar to what Gmail provides.